Rose City's bright idea
LED streetlights will save money, energy
When David Nemo, president of Rose City Astronomers, wants to stargaze for an evening he heads out to a favorite spot or two in the Columbia Gorge. The view isnt nearly as clear as out by Prineville or Maupin, but its passable, and accessible.
You can see traces of the Milky Way, depending on whether the moons up or not, Nemo says.
Unspoken, but understood, is that Nemo and his fellow stargazers long ago learned they cant see much from within Portlands city limits. But that soon should change.
The city of Portland has begun replacing its 55,000 mostly high-pressure sodium vapor street lamps with light-emitting diode (LED) lights. The two-year, $18.5 million project represents the single-largest energy-efficient project the city has ever done, by a large margin, according to Michael Armstrong, Portlands sustainability manager.
LED fixtures are expected to save the city $1.5 million a year in reduced energy and maintenance costs. Currently, streetlights represent about a fifth of the citys electrical bill. The LED lamps will reduce energy usage in each lamp by about 60 percent. That means a total reduction in city electrical usage by 12 percent, or about 20 million kilowatt hours a year. In addition, the LEDs come with a 10-year guarantee. In about 10 years the savings from reduced electrical usage, along with reduced maintenance, should have paid off the costs of the changeover.
The LEDs also open up a world of programmable opportunities. Some day, city engineers may be able to save energy by instantly dimming lights on roadways when no cars are around, or they might turn street lamps on and off to direct police to emergency situations, according to Scott Kardel, acting executive director of the Tucsons International Dark Sky Association.
Chattanooga, Tenn., installed 350 LED lamps in a gang-infested park and gave police the ability to turn individual lights on and off from their squad cars when they wanted to disperse groups. Portland Bureau of Transportation engineers have talked about possibly using the LEDs to brighten up the Old Town Entertainment District after the bars close, once the new lamps are installed.
Looking down on the city
And one not insignificant side effect will be a dramatic reduction in the light pollution that keeps amateur astronomers such as Nemo from getting a clear view of the night sky. LEDs basically point down like spotlights rather than emitting the more diffuse pink/orange light of high-pressure sodium lamps. Each 29-watt LED lamp that replaces a 100-watt sodium bulb is comprised of 12 small lights that can be directed to spaces along a sidewalk or roadway.
It will certainly change the character of the way the city looks at night, Kardel says. If youre flying at night over Portland and looking down, you shouldnt see any glare that shines at you.
The LEDs will cast a brighter, broader spectrum light with better color rendering, says Peter Koonce, Manager of Signals & Street Lighting for the city of Portland. The changeover is being financed through a bond measure approved by the City Council in 2012.
Portland being Portland, the city couldnt replace all its street lamps without going through a process. In this case, transportation bureau spokeswoman Diane Dulken says, the decision on which street lamps get replaced first is being viewed through an equity lens. Mostly, that means lower-income neighborhoods are getting LEDs first.
The transportation bureau used the Coalition for a Livable Futures equity atlas, which details Portland neighborhood demographics to map out its lamp replacement schedule.
What we wanted to do at the end of the day is say we didnt single out any one income or any one race, Koonce says. Seattle didnt take neighborhood demographics into account when it changed to LEDs, Koonce adds, and the city got complaints.
New Columbia in North Portland already has had its lamps changed to LEDs, and work has begun on a number of outer Southeast Portland neighborhoods. One thing the city isnt doing, according to Koonce, is waiting for the old bulbs to die before replacing them with the new LEDs. Koonce says other cities have tried that and failed the equity test.
What they were finding out was they were only getting complaints from the higher-income neighborhoods, he says.
Biogas generators also save
Changing the citys streetlights to LEDs in itself gets the city above the 7 percent carbon emissions reduction target outlined in the international Kyoto Protocol, says sustainability manager Armstrong. Incidentally, the second-biggest energy savings project the city has ever undertaken was the introduction of biogas electrical generators at the citys wastewater treatment plant on North Columbia Boulevard. Those generators produce about 12 million kilowatt hours a year not even close to the 20 million kilowatts per year the LEDs are expected to save.
Kardel, of the International Dark Sky Association, is more concerned about another kind of energy. His organization lobbies worldwide for a return to the truly dark night skies that existed long ago. He cites studies showing our nighttime light pollution is responsible for all sorts of modern-day problems, from disruption of animal mating and migration patterns, to sleep deprivation in people whose circadian rhythms are thrown out of whack.
Kardel isnt saying that the switch to LED streetlights will completely erase light pollution. Sodium lamps in privately owned parking lots remain a problem. But, Kardel says, the reduction in Portlands light pollution should be significant in many ways.
Until modern times, this was something everybody got to see, Kardel says. Every clear night for all of human history the stars have been an amazing source of inspiration for art, for science, for literature and philosophy and religion. We dont have any way of knowing what impact that has today, that not being around.
City traffic signals becoming more efficient
Portlands Bureau of Transportation is waving the efficiency flag in justifying changing the citys street lamps to LEDs.
A look at ways the bureau is embracing efficiency is especially relevant as Transportation Commissioner Steve Novick battles for a street fee that would give his bureau more funds.
Peter Koonce, manager of Signals & Street Lighting for the bureau, is particularly proud of a couple of new twists in the way traffic signals are about to be used.
One will give trucks priority over cars at traffic signals. Detectors buried in some roads will identify trucks heading toward traffic signals and hold the green so they can get through without stopping.
Before all you car drivers get up in arms, heres the logic: From a traffic efficiency point of view, Koonce says, the worst place for a truck is first in line at a red light. Trucks are slowest to accelerate from a stop, so they slow down all the traffic behind them. And thats especially true at an uphill stop.
The first truck priority signals are going in on North Columbia Boulevard and around Swan Island, which both see a lot of truck traffic.
Koonce says at some stoplights the new detectors will virtually eliminate trucks having to stop, and also make pedestrians safer. Among the greatest dangers to pedestrians currently crossing Columbia, he says, are trucks trying to stop short at signals turning yellow or red.
Another new traffic efficiency initiative has the Bureau of Transportation installing even smarter traffic signals. About 60 percent of Portland stoplights already have roadbed detectors that hold greens for vehicles speeding toward the lights. The idea there, again, is to keep pedestrians safe from cars or trucks that might try to beat a yellow light and crash into pedestrians starting to cross on a Walk signal.
The bureau is experimenting with a microwave detector at Southeast Powell and 24th Avenue that can manage the traffic signal to deal with traffic backing up. Within the next few months that signal will be turning green or red based on the traffic conditions on Powell up to three blocks away.
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